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Just wanted to share some pictures of my newly acquired high vacuum equipment that I have recently obtained. As mentioned in a couple of prior posts, I will be working on constructing a rather large, multi-purpose high vacuum system to accommodate a wide range of experiments, ranging from fusor applications, to ion beams, electron beams, and general plasma physics.

My first piece of equipment is the center of my system design, consisting of a large custom welded stainless steel vacuum chamber I found off ebay. I had been scouring ebay for a few years looking for chambers, and I couldn't pass this beauty up. The chamber has an internal bore of 8" and a total height of 28". It has 21 conflat ports of the following sizes: (x2) 10", (x1) 8", (x2) 6", (x5) 4.5", (x9) 2.75", and (x2) 1.33" ports. Only $250 on ebay, and all the knife edges are in excellent condition, with only scratches on the bottom input port, and a little bit of rust here and there and some dust inside. It is on the heavy side, weighing in at 100lbs, so mounting and moving this thing is gonna be a real pain. Earlier this week I went in with a toothbrush and some baking soda and scrubbed out the minor rust spots, gave it several washes with mildly soapy water, a thorough wipe down with mineral spirits, and further washing and drying to remove any residue left, and have it currently sealed up with aluminum foil over the ports (the pictures below are prior to cleaning and sealing up). Since it will be quite a while before I start piecing it together and pulling vacuum, I will be placing a large bucket of desiccant inside the chamber with all the ports closed up to keep moisture down to a minimum while in storage. I will do a more rigorous cleaning as I install blanks and assemble the unit as I go.

The second piece of equipment is an Edwards EO4 600L/s diffusion pump. I ended up getting three for free - one (photo below) is in near brand new condition, barely used, and the other two are still hermetically sealed, never been used units.

The last piece of equipment just arrived today, and is another awesome ebay find. It is a combination pneumatic-actuated gate valve/butterfly valve combo with an additional side pumping port, which is perfect for what I am looking for, and solves a lot of issues and costs of finding and mating two separate units. The internal bore of the system is 6", which allows me to keep an extremely high throughput in the system to my main chamber (the diffusion pump has a diameter of about 5"), in addition to having high vacuum isolation and throttling control. The seller tested the pneumatic actuation and stated it worked without issue, but was being sold as-is since they could not perform high vacuum testing on it. Its original price was almost $300, but they accepted an offer for $100. Looking over the whole unit, it seems like it is in terrific condition. Looks very new with no scratches, scuffs, or rust. The butterfly valve turns smoothly, and the gate valve is very solid and at this point appears to fully seat. The only downside is that the system is very heavy as well, about 70lbs, which means the total weight of my system is going to be very heavy. But if it checks out and is vacuum tight it will be well worth it, especially for the bargain price I got it at.

This whole endeavor is going to be a very long term and continually evolving process. I have roughly broken down my workflow to several major phases, and am currently in the process of cadding out and designing to full Phase I system. My first objective is to build a mobile support cart from 8020 to house the major components, in addition to blanking off the entire chamber and mating all of the major parts to the chamber. I also plan on building and integrating a water-cooled baffle and an additional peltier-pumped cold trap. Once this is accomplished, I will begin to work on pumping down and conditioning the whole chamber, which will include extended pumping times, leak checking, partial baking with heat tapes around the chamber, and possibly simple plasma cleaning. I have been doing vacuum calculations to give estimates of outgassing rates, pump requirements, etc, as well to start preparing for this endeavor. My ultimate goal is to be able to reach a final pressure of around 10^-6 torr, which I believe should be achievable with the pump I have and following proper high vacuum handling and preparation, though I will be more than happy to reach 10^-5 torr in the beginning. After I establish a reasonable vacuum, I will begin to slowly add equipment to the chamber. At this point, I plan on adding 4 ion guns, one for each of the 45 degree ports at the top, a fusor grid, an electron beam source, a magnetron sputtering gun, ion/plasma engine for space propulsion testing, simple mass spectrometer, and a laser interferometer for plasma density diagnostics. I will be cadding these basic systems and adding them to my overall master model as I go. At this point since I have a limited budget each month, physical progress will be very slow, but I will be at least updating the design work and cad models and posting them as I go along to show the conceptual design of the system, as well as whatever electrostatic simulations I do for various parts, such as the ion guns.

I keep trying to say this to many beginners - really good deals can still be obtained on ebay and the like; one needs to know what to look for, understand their own limitations (what they can handle relative to machine work, and/or welding and general jury-rigging), and then be patient as they search daily.

Any one here want to pay for the D2 needed to work those volumes on a continuously leaked differential pumping basis?! I once had a rather large volume setup like this and had big ideas, but sobered up quickly and sold it at a great profit to a fellow that had not the wisdom to figure it all out.

Stuff in this effort that is acquired like this assembly, ($5000 dollars worth of vacuum stuff for $150.00 or even free), can be a real magnet to the eyes, mind and pocket book, up front. However,as the mind mulls over the future of a monster like this, sitting in the corner of the room, and the pocket book starts blanking off some of those giant holes in the system at list prices, the realization of the futility of the effort sets in rather quickly.

Richard Hull

Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Thanks for the comments and input. Over the past couple of months since my initial post, I have been doing a lot of CAD designing and project planning for my endeavors. While this chamber certainly has the potential for very large neutron yields (by amateur fusor standards), this chamber will be dedicated purely to other non-neutron larger scale ion beam, plasma, and space thruster testing and design at this point. I would also have issues running something this large in my current location, and for what I want to do, I don't really need or want large neutron fluxes. I think the thing that makes this the most challenging is the actual weight of the whole system - with the valves, blanks, pumps, and chamber itself, I am more worried about weight and moving this around than anything else. While cost is also the number one setback at this point, I am not particularly in a rush, and can take my time to slowly build up parts for this - this was supposed to be my very long term tech project anyway. However, I definitely think that what Richard Hull said rings true - a massive system like this for a low cost is real tempting at first, but the sheer size makes the logistics of running this make this more challenging and expensive than I initially anticipated. Still, it's a beautiful piece of science equipment, and even though it is currently sitting in the corner, it's cool to think that maybe one day I might be able to do some really advanced science with this thing.

I have however started planning and gathering parts for a small, portable system that will be fusion capable based off of 2.75" conflat hardware. I have designed this system with some extra valves and port options to be able to accommodate a wide range of projects other than just a fusor - I am actually more interested in beam-on-target systems than the fusor, and would probably focus on those efforts rather than a fusor. I have most of the major parts now, and really just need to machine the adapter plate between the diffusion pump and the chamber inlet, and get the remaining KF25 hardware I will be using for other parts of the system. I wanted to have a large amount of control and inputs while also having the most direct pumping throughput and keeping cost down. I was able to snag a ton of excellent deals on ebay, so the cost has been very good so far. I will post pictures of my parts and cad models for this miniature chamber. Unfortunately, it won't be for quite a while longer until this gets up and running - a lot of other financial obligations have come up now, putting these vacuum projects on hold, and another major project that I started over a year ago (building my dream version of a shamisen, a Japanese three string instrument) currently takes priority, and due to the nature of it being a very high end and completely custom instrument it will be severely draining my budget for the foreseeable future. That being said, I will still be coming up with both cad model designs and well as various simulations (electrical, thermal, and particle interaction) for my projects and would like to still update and post them (it gives me a chance to at least work on them for free, even if not physically.)

This was a perfect 16" hemisphere that cost the folks who ordered it $$$$$. Their need fell through with the loss of a contract, and I was offered it at a killer price. $600.00 later, I moved this fabulous new, unused monster into my lab.

As I started to blank off the many ports, I thought of the Deuterium needed to flow through this monster. I thought of the new, bigger vacuum system needed to pump it down and the time needed to pump it to a functional level.

Once I reeled my brains in and got the expensive bragging rights all done, I sold it and what blank-offs I had assembled to a well heeled fellow who felt he could make a killer fusor out of it. It sits today in his lab, much as it sat in my lab. Whew.....Dodged the bullet on that one.

Richard Hull

Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Chamber size alone is not the only issue - foot print matters, as well. The stand and fore pump will take up a lot of room. Still, the SS covers, fittings and various steel piping/valves will not be cheap - I know relative to that for my high vacuum system (accelerator project - its foot print is ridiculously large considering how small the actual gun is and the need for purity drives using an air dyer system (home made) and all SS fittings/tubes.)

Then there are wall outlet issues - big systems often require power hungry devices/supplies that can cause outlet issues - i.e. too few. Or bigger supplies can necessitate 220 v requirements. These, unless one has a place that already meet these needs, can also lead to problems. And can add phantom cost when one has to add electrical and possibly water costs to the bill besides the loss of house or garage space that was used for other purposes.

Secondary systems can be an issue - power supplies and detector control boxes really take up space besides often necessitating mini-racks; to add insult to injury, they too too continue to add to the over all costs/space issues. These are areas that are far too often easily overlooked for large chamber projects - problems like support services and instrumentation on large systems have a life all there own and eat up both dollars and time (large begets large - lol)

While you covered blank-off's, the issue with those is that at some point, since a chamber has all these access point, one tends to fill them with devices/sensors/feed-thru's etc and those can really get costly if one isn't ready/able to do a lot of jerry-rigging and small/detailed machine work (I know - my accelerator requires five extremely complex feed-thru systems that needed to be leak tested and use very specialized components.)

The back-bone of any large vacuum system (the chamber & main high vacuum pump) while critical, too often is only the tip of an iceberg for the project and just the starting point for work and costs. Finally, and as this poster adds, large chambers eat up one's time in a fashion that can overwhelm even a seasoned veteran in with extensive vacuum and electronic knowledge.

When one thinks large, one needs to consider all the 'large' demands that are created, too.

Space can and will be made for a giant system if that is one's goal and "got th' fever". However, it is usually all about money and rarely logic that stops the head-strong fellow with grandiose ideas related to a mega-fusor project. Any one worried about volumetric spacial requirements usually has no money. At least, they have not the money required for such an effort without alarming the wife and not being able to put shoes and new clothes on the kids for the next 5 years.

Richard Hull

Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.